It is the case that if an instrument change occurs in the middle of a bar, rests can go missing, but I can't see any reason why the instrument change should occur in the middle of the bar in your case, so being able to take a look at the project file would be helpful.

FWIW, I noticed that in the full score, page 6 ends with bar no.39. At the start of page 7 there is no bar no., but the system has two bars, and the following system starts with bar 41... In Galley view this is bar 42...

Chase, it looks like you've revised the music since you posted the initial screenshot and have filled bar 48 with music, so at least the right number of beats are found there. I can't diagnose the reason for the broken multi-bar rests myself even with your project, but I will pass it on to the man who can and will report back when I have more information.

Sorry to take so long to come back to you on this one, Chase. We have looked into this and have narrowed down the problem to the fact that you have (probably inadvertently) used staff-specific (or as we sometimes call them "local") time signatures. When you created the 9/8 time signature in bar 40, it looks like you accidentally created the 9/8 time signature on the English Horn staff either by Alt+clicking it onto that staff from the panel or by hitting Alt+Enter when you created it via the Shift+M popover. Even though the global and local time signatures here happen to be identical, Dorico doesn't consider the Oboe and English Horn staves equivalent, and so it won't show multi-bar rests in that passage.

I've got a separate issue with multimeasure rests and instrument changes. In Page View, on one of my layouts, multimeasure rests aren't displaying correctly. I can work around with a system break. There's a double bar, a rehearsal number, and a key change where the multimeasure rest should break.

Yes, we're sorry about this bug. It will be fixed in the small update coming very soon (hopefully before the end of the month, barring any unforeseen delays that would prevent us from releasing it when we plan to).